<!doctype html>
<html>
<head>
  <meta charset="utf-8">
  <title>{% block title %}{% endblock %}</title>
</head>
<body>
    {% block head %}    
    <!-- 把子模板的东西放进对应的块中！ -->
    {% endblock %}
    {% include "head.html" %}  
    <!-- include 属于把 a 植入进 这里 -->
    {% block content %}
    {% endblock %}
</body>
</html>